1. Field of the Invention
This invention relates generally to an improved system for the containment and transfer of contaminated gases which are formed by fluid chemical and petroleum products disposed in a storage tank. More specifically, the invention relates to an improved fluid transfer system for tanker vessels such as oil tankers for reducing air pollution which contains and controls the distribution of contaminated air, particularly air contaminated by hydrocarbon gases, disposed in land storage tanks during refilling of such storage tanks with fluid chemical and petroleum products carried by the tanker vessel so that the contaminated air is prevented from escaping to the atmosphere.
2. Description of the Prior Art
The transfer of petroleum and chemical products to and from tanker vessels is generally accomplished at present simply by movement of the fluid chemical and petroleum products from the cargo tanks of the tanker vessel to land storage tanks. No attempt is made to capture or contain contaminated air located within the land storage tanks being filled or, if the tanker vessel is being loaded, the cargo compartments of the tanker vessel. In contrast, the contaminated air is simply vented to the atmosphere during filling of such tanks.
Hydrocarbon vapor formed by petroleum products is, at present, discharged into the atmosphere in large quantities. Such discharges are particularly common at refineries as refinery tanks are filled by tankers and as tankers ballast their cargo tanks after the completion of the discharge of their cargo and during cargo transfer operations on the tankers. At present, approximately 7.5 million barrels (315 million gallons) of fuel for transportation systems are consumed in the United States each day. The handling of this volume of fuel results in the discharge of approximately 168 million cubic feet of hydrocarbon gas to the atmosphere each day in the United States, a significant portion of which results from the transfer of fluid petroleum products between tanker vessels and refinery land storage tanks. These hydrocarbon gases, as well as the gases produced by fluid chemical products, are a major cause of air pollution. Moreover, the presence of such vapors presents a safety hazard in work areas and public places.